Press for hydrostatic extrusion

ABSTRACT

A press for hydrostatic extrusion includes a press stand and a high pressure cylinder displaceable in the stand. A punch is mounted for movement into the high pressure cylinder to produce the extrusion pressure therein. The billet and die are positioned by a manipulating arrangement between the open end of the high pressure cylinder and a die support, and the cylinder is moved over the billet and die. Pressure fluid is then introduced through the die support and die into the pressure chamber, flow of the fluid out of the chamber being prevented by a valve arrangement or by seating of the billet against the die. The punch is then advanced into the pressure cylinder to produce extrusion.

O Umted States Patent [1 1 [111 3,709,014

Landa et al. 14 1 Jan. 9, 1973 54 PRESS FOR HYDROSTATIC 2,558,035 6/1951Bridgman ..72/60 EXTRUSION 3,440,849 4/1969 Hardy et al ..72/6O 3,1 3 l9[75] Inventors: Torstein Landa; Pertti Syvakari; 26 096 I 64 Gerard eta]72/60 Erikd wesunan an of vasteras' Primary Examiner-Richard J. HerbstSwe en Attorney-Jennings Bailey, Jr. [73] Assignee: Allmanna SvenskaElektrlska Aktiebolaget, Vasteras, Sweden ABSTRACT [22] Filed: April 28,1971 A press for hydrostatic extrusion includes a press stand and a highpressure cylinder displaceable in the [2]] Appl 138301 stand. A punch ismounted for movement into the high pressure cylinder to produce theextrusion pres- [30] Foreign Application Priority Data sure therein. Thebillet and die are positioned by a manipulating arrangement between theopen end of Apr1l30,1970 Sweden ..60l0/70 the high pressure cylinder anda die support, and the cylinder is moved over the billet and die.Pressure ill fluid is then introduced through the die Support and [58] c72/60 die into the pressure chamber, flow of the fluid out of a thechamber being prevented y a valve arrangement or by seating of thebillet against the die. The punch is [56] References Cited then advancedinto the pressure cylinder to produce UNITED STATES PATENTS extruslon-3,531,965 10/1970 Nilsson ..72/60 6 Claims, 18 Drawing Figures 5.9 56 9743! I2 fl PATENTEDJAN 91975 3,709,014

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INVENTORS "@RSFEIN LANDF B PERTH SWAKAR ERH w EST/MA" PRESS FORHYDROSTATIC EXTRUSION BACKGROUND OF THE INVENTION 1. Field of theInvention The present invention relates to a press, preferably ahorizontal press, for hydrostatic extrusion of a billet enclosed in ahigh pressure chamber.

2. The Prior Art Presses for hydrostatic extrusion normally have ahorizontal high pressure cylinder which is displaceable in a press standand which, together with a die with an opening, which can project intothe cylinder, and a pressure-generating punch insertable into thecylinder, forms a closed chamber. A billet to be extruded is placed inthe pressure chamber, after which the chamber is filled with a pressuremedium. The insertion of the pressure-generating punch into the pressurechamber generates a pressure in the pressure medium which acts uniformlyfrom all sides on the billet and tends to press it out through the die'opening so that a rod is formed with the cross-section of the dieopening. The pressure required for the extrusion depends partly on thematerial of the billet and partly on the area reduction ratio, by whichis meant the ratio between the cross-section of the billet used and thecross-section of the product. The area reduction ratio which can beachieved increases sharply with increased pressure, but the strength ofthe pressure chamber limits this pressure. NOwadays it is possible tooperate in the range of kbar during regular production.

It is desirable to completely fill the pressure chamber with a liquidpressure medium in order to be able to aChieve extrusion pressure withthe least possible displacement of the pressure-generating punch. If thepressure chamber is not completely filled it means that there is acertain volume of gas therein when the pressure-generating punch isbeing pushed in. Since the gas is more compressible than a liquid, thecompression of the gas causes a relatively large and undersireddisplacement of the pressure-generating punch. The volume of the gascauses the useful volume of the pressure chamber to decrease. The amountof billet which can be extruded is decreased to the same extent.

One method of filling a pressure chamber is shown in US. Pat. No.3,531,965 in which the pressure cylinder is provided on the punch sidewith a chamber for the supply of liquid while the cylinder is beingpushed in over the die so that the pressure chamber is closed. Duringeach operating cycle the pressure-generating punch must be drawn out ofthe high pressure seal which forms the seal between the cylinder and thepressure-generating punch. Seals for extremely high pressure which sealbetween two parts movable in relation to each other are extremelysensitive to damage and such damage normally occurs when the punch isinserted through the seal.

SUMMARY OF THE INVENTION The invention provides a press for hydrostaticextrusion including a press stand and a high pressure cylinderdisplaceable in the stand. A punch is mounted for movement into the highpressure cylinder to produce the extrusion pressure therein. The billetand die are positioned by a manipulating arrangement between the openend of the high pressure cylinder and a die support, and the cylinder ismoved over the billet and die. Pressure fluid is then introduced throughthe die support into the pressure chamber, flow of the fluid out of thechamber being prevented by a valve arrangement or by seating of thebillet against the die. The punch is then advanced into the pressurecylinder to produce extrusion.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further describedwith reference to the accompanying drawings.

FIGS. 1 8 show a complete operating cycle in a press according to theinvention.

FIG. 9 is a view from above showing operating cylinders for moving thehigh pressure cylinder of the pressure chamber. (The manipulator deviceof FIG. 10 is omitted).

FIG. 10 is a section on the line AA of FIG. 1 showing a side view of amanipulator device for inserting a billet and a die.

FIG. 11 shows on a larger scale the right end of the high pressurecylinder with an inserted billet and die and an injecting deviceinserted'in the die support.

FIGS. 12-15 show four positions of an operating cycle in a pressdesigned to be loaded through the press yoke.

FIG. 16 shows on a larger scale the right end of a press of FIGS. 12-15with a billet, a die and die support inserted in the high pressurecylinder and an injecting device inserted in the die support.

FIG. 17 is a section on the line B-B of FIG. 12, showing the movablepressure distributing plates for taking up die forces.

FIG. 18 shows on a larger scale the billet holder used and thesurrounding parts of the high pressure cylinder.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, 1 designates ahorizontal press stand. A horizontal high-pressure cylinder 2 is axiallydisplaceable in this stand. As shown in FIG. 9, the high pressurecylinder 2 is displaced by two hydraulic cylin-' ders 50, attached tothe press stand 1 by brackets 51. The piston rods 52 are connected tobrackets 53, which are attached to the cylinder 2. The cylinders areconnected to a pressure medium source (not shown) by conduits 54 and 55.On the left end of the press stand there is an operating cylinder 3 witha piston 4 shaped as a differential piston and connected to apressuregenerating punch 5 which penetrates into the highpressurecylinder 2 and generates the pressure necessary for the extrusion in thepressure chamber 30 which is formed by the cylinder 2, punch 5 and a die6 projecting into the opposite opening of the cylinder. The spaces 7 and8 on either side of the piston communicate through a bore 9 and aconduit 56 passing through a hole 57 in the press yoke and a bore 10 anda conduit 58 passing through a hole 59 in the press stand 1 withoperating valves (not shown) and with a pressure medium source. In thehigh pressure cylinder 2 is a sleeve 11 and seals 12 and 13 which sealbetween the cylinder 2 and the punch 5 and the die supports 14 or 15,respectively. During a normal operating cycle the punch 5 is never drawnout of the seal 12, something which considerably contributes toincreasing the length of life of this seal 12 which is extremelysensitive to damage because of the movement between the punch and theseal under high pressure. In the sleeve 11 a billet-holder 16 is axiallymovable. This holder 16 is shown in a larger scale in FIG. 18. hisprovided with a projecting guide bar 18 which runs in a slit 19. Themovement is limited by stop surfaces 20 and 21 at the ends of the slit.The billet-holder also includes a spring member 22 which-presses thebillet 23 against the die 12 before compression is initiated. The holderhas a bore 60 and in one end a seat 61 for the spring 22. In this seatthere is an opening 62 allowing pressure medium to pass through theholder. The end facing the billet is formed as a funnel with slopingsides 63 for guiding the billet 23 into the bore 60.

The press according to FIGS. 1 9 has a die support 15 which is made inone piece with the pressure-distirbuting plate 24 which transmitspressure to one yoke 25 of the press stand. The pressure cylinder can bemoved so far to the left that a billet 23 and a die 6 can be insertedfrom the side between the cylinder 2 and the die support 15 by means ofamanipulator 65 so that billet and die come opposite the opening of thecylinder 2. In FIGS. 1 and 8 only gripping members 26 and 27 of themanipulator 65 are shown. The manipulator 65 comprises, as shown in FIG.10, a lever 66, pivoted on shaft 67, carried in a bracket 68,'attachedto the press stand 1. Only the gripping member 27 for holding the die 6can. beseen in FIG. 10. The gripping members consist of a lower lowerpart 27a, fixedly attached to the lever 66, and an upper part 27bpivoted between two brackets 69 on the lever 66 and provided with alever 70.. An operating rod 71 of an operating cylinder 72 is connectedto the lever 70. The cylinder 72 is pivoted between the two brackets 75on the lever 66, and connected to control valves and a pressure mediumsource (not shown) by conduits 74 and 75. An operating rod 76 f anoperating cylinder 77 is pivoted in the upper end of the lever 66. Thecylinder 77 is also pivoted in the bracket 68. By means of conduits 78and 79, it is connected to control valves (not shown) and a pressuremedium source. a

In the following a complete operating cycle will be described. Atthestart of an operating cycle the highpressure cylinder has been pushed asfarm the left as possible as shown in FIG. lpA billet'23and a die 6 areplaced by the manipulator 65 opposite to the opening of the cylinder 2,after which the billet and the die are moved towards the die support andthe cylinder is moved to the right over the billet until spring 22 ofthe billet holder 16 comes into contact with the billet 23. The billetholder may be provided with friction elements so that it does not runeasily in the cylinder and a force is thus obtained which presses thebillet 23 and the die towards the die support 15 during the latter partof the displacement of the cylinder 2 when the manipulator fingers26'and27 must be removed so as not to prevent the movement of the cylindercompletely in over the billet and the die so that the pressure chamber30 is entirely closed (see FIG. 2). At this stage oil may be injected inthe gap between the billet 23 and the opening in the cylinder 2 so thatthe chamber is substantially filled with pressure medium. Upon furthermovement of the. cylinder 2 to the right the pressure medium spacebetween the billet and the cylinder in the pressure chamber 30 isdecreased, whereupon mostly air is forced out during continued closingof the pressure chamber. When the pressure chamber is completely closed,the billet holder 16 is in its lefthand limit position which isdetermined by the stop surface in the slit 19 of the sleeve 1 1, inwhich slit the guide bar l8joined to the billet holder runs. The lengthof the billet is such that the spring member 22 is compressed during thelatter part of the movement of the cylinder 2 so that a desired pressureis obtained against the billet 23 so that this and the die are pressurewith the desired force against the die support 15. The pressuregenerating punch is moved at the same time to the right so that it isnot withdrawn from the seal 12 (see FIG. 3). As

shown ,in FIGS. 4 and 11, an injection tube 31 with a seal 32 isinserted into the pressure-distributing plate 24 joined to the diesupport 15 and pressure medium from a source, not shown in the drawings,is supplied at a high pressure to the pressure chamber 30; By highpressure is meant a pressure of-at least 25 bar, but usually thepressure is considerably higher, preferably betweenlOO and 500 bar. Anyair remaining in the pressure chamber 30 is compressed so that itsvolume is so negligible that this quantity of air can. be accepted inthe pressure chamber since it only negligibly affects the movement ofthe pressure-generating punch 5 when the pressure-generating punch 5when the pressure is increased to extrusion level. When the pressuremedium is supplied, either the die is lifted from the die support asshown in FIG. 11 and pressure. medium passes between the die and the diesupportand through opening 33 out into the pressure chamber 30, or thebillet 23 is lifted from the die 6 as shown in FIG. 16. When'theinjection tube 31 is removed, the die 6 and die holder 15 or the billet5 and die 6 form valve members in a valve which prevents pressuremediumfrom flowing out of the pressure chamber 30. The pressure chamber30 is now almost entirely. filed with pressure medium. The position isshown in FIG. 5. Pressure medium is now supplied tothe space 7 in theoperating cylinder 3 so that the pressure-generating punch 5 is pressedwith great force into the cylinder 2 and generates the pressurenecessary for extrusion in the chamber 30. FIG. 6 shows the position inthe middle of the extrusion process itself. In the position shown inFIG. 7,-the extrusion is interrupted and the cylinder 2 is returned withthe operating punch 4 and punch 5 to its lefthand limit position asshown in FIG. 8; The die '6 with the remainder of the billet 35 is thenremoved form the support 15 and a cutting machine 33 cuts the extrudedproduct 34 between the die 6 and die support 15. A new operating cyclecan then be started.

FIGS. 12 to 16 show a press according to the invention in which thebillet is inserted into the cylinder through the opening 40 in one yoke25 of the press stand 1. The opening 40 must then be of such a size thata manipulator, not shown, can be inserted through it with the billet 23,die 6 and die support 14. The pressure against the die support 14 istransmitted to yoke 25 by a divided pressure-distributing plate 41consisting of two equal parts 41a and 41b which can be operated betweena closed and an open position. FIG. 17 shows the arrangement of theplate parts. The parts 41a and 41b are guided by two guide members 80and connected to the piston rods 81 and 82 of the operating cylinders 83and 84 attached to the press stand 1.'The

cylinders are connected to control valves and a pressure medium source(not shown) by conduits 85, 86, 87 and 88. The plate members 41a and 41bcan be moved by means of the cylinders 83 and 84 between the forceabsorbing position shown in FIGS. l4, l6 and 17 and a withdrawn positionshown in FIGS. l2, l3 and in which position a billet can be loadedthrough the opening formed between the plate members by means ofmanipulator means. Before the manipulator is withdrawn, a tubular rod 42is inserted in the die support 14 to inject pressure medium into the nowclosed pressure chamber. This has a shoulder 43 so that it can keep thedie support pressed into the cylinder opening while the two parts 410and 41b of the pressure-distributing plate 41 are brought together.Pressure medium is then injected into the pressure chamber (see FIGS. 13and 14). After the extrusion the support parts 41a and 41b are pulledapart and the die support 14 and the die 16 with the remainder of thebillet 35 are withdrawn through the opening 40 in the yoke 25 of thepress stand (see FIG. 15). A cutting machine 33 then cuts the extrudedproduct 34 near the die 6 and the remainder of the billet 35 is removedfrom the die, after which this can be used again. In this embodiment,the cutting takes place completely outside the press itself, whichdecreases the risk of metal chips coming between the various parts ofthe press causing trouble during operation. The extrusion cycle isotherwise similar to that previously described.

Of course the invention is not limited to the embodiments shown. Manyvariations are feasible within the scope of the following claims.

We claim:

1. Press for hydrostatic extrusion comprising a press stand, a pressurechamber which is formed by a high pressure cylinder open at one enddisplaceable in the press stand, a die support at one end of the pressstand, a die insertable between the open end of the cylinder and the diesupport and having an opening to shape a product, a punch projectinginto the other end of the cylinder to generate a pressure in apressuremedium enclosed in the pressure chamber necessary for extrusion of abillet, means for operating the pressuregenerating punch and the highpressure cylinder, a mechanism for positioning a billet and the diebetween the open end of the high pressure cylinder and the die support,and a billet holder in the cylinder to hold the billet against the diebefore the extrusion process, in

which the press is provided with insertable and removable means forinjecting pressure medium into the pressure chamber through the diesupport for filling the pressure chamber and placing it under pressurebefore increasing the pressure to extrusion level by inserting thepressure-generating punch, and with means to prevent pressure mediumfrom escaping from the pressure chamber while the injection means isbeing removed.

2. Press according to claim 1, in which the means to prevent escape ofpressure medium includes a surface on the die engageable with the frontpart of the billet to form a valve means sealing against the seat.

3. Press according to claim 1, in which the means to prevent escape ofpressure medium includes a valve means in which the die support formsthe valve seat and the die is movable with respect to the die supportand seals against the seat.

4. Press according to claim 1, which includes a billet holder which isaxially movable in the high pressure cylinder and which centers thebillet at its inner end and a spring engaging the billet holder to pressthe billet against the die.

5. Press according to claim 1, in which a high pressure seal is providedbetween the high pressure cylinder and the punch unit, the means foroperating the high pressure cylinder and the punch includes means tokeep the punch always inserted so far into the high pressure cylinderthat its front end is always inside the high pressure seal between thepunch and the cylinder.

6. A method of operating a press for hydrostatic extrusion whichcomprises a press stand, a pressure chamber which is formed by a highpressure cylinder open at one end displaceable in the press stand, a diesupport at one end of the press stand, and a punch projecting into thecylinder to generate a pressure in a pressure medium enclosed in thepressure chamber necessary for extrusion of a billet, which methodcomprises inserting a billet and a die between the open end of the highpressure cylinder and the die support, advancing the high pressurecylinder over the billet and the die, injecting pressure medium into thepressure chamber through the die support for filling the pressurechamber and placing it under pressure while preventing pressure mediumfrom escaping from the pressure chamber and increasing the pressure toextrusion level by advancing the pressure-generating punch.

1. Press for hydrostatic extrusion comprising a press stand, a pressurechamber which is formed by a high pressure cylinder open at one enddisplaceable in the press stand, a die support at one end of the pressstand, a die insertable between the open end of the cylinder and the diesupport and having an opening to shape a product, a punch projectinginto the other end of the cylinder to generate a pressure in a pressuremedium enclosed in the pressure chamber necessary for extrusion of abillet, means for operating the pressure-generating punch and the highpressure cylinder, a mechanism for positioning a billet and the diebetween the open end of the high pressure cylinder and the die support,and a billet holder in the cylinder to hold the billet against the diebefore the extrusion process, in which the press is provided withinsertable and removable means for injecting pressure medium into thepressure chamber through the die support for filling the pressurechamber and placing it under pressure before increasing the pressure toextrusion level by inserting the pressuregenerating punch, and withmeans to prevent pressure medium from escaping from the pressure chamberwhile the injection means is being removed.
 2. Press according to claim1, in which the means to prevent escape of pressure medium includes asurface on the die engageable with the front part of the billet to forma valve means sealing against the seat.
 3. Press according to claim 1,in which the means to prevent escape of pressure medium includes a valvemeans in which the die support forms the valve seat and the die ismovable with respect to the die support and seals against the seat. 4.Press according to claim 1, which includes a billet holder which isaxially movable in the high pressure cylinder and which centers thebillet at its inner end and a spring engaging the billet holder to pressthe billet against the die.
 5. Press according to claim 1, in which ahigh pressure seal is provided between the high pressure cylinder andthe punch unit, the means for operating the high pressure cylinder andthe punch includes means to keep the punch always inserted so far intothe high pressure cylinder that its front end is always inside the highpressure seal between the punch and the cylinder.
 6. A method ofoperating a press for hydrostatic extrusion which comprises a pressstand, a pressure chamber which is formed by a high pressure cylinderopen at one end displaceable in the press stand, a die support at oneend of the press stand, and a punch projecting into the cylinder togenerate a pressure in a pressure medium enclosed in the pressurechamber necessary for extrusion of a billet, which method comprisesinserting a billet and a die between the open end of the high pressurecylinder and the die support, advancing the high pressure cylinder overthe billet and the die, injecting pressure medium into the pressurechamber through the die support for filling the pressure chamber andplacing it under pressure while preventing pressure medium from escapingfrom the pressure chamber and increasing the pressure to extrusion levelby advancing the pressure-generating punch.